The document summarizes a research study that aimed to identify and rate factors affecting the accuracy of cost estimates in Jordanian construction projects. The research involved formulating objectives and hypotheses, collecting data through questionnaires from 170 contractors and 95 consultants, exploring the data, and developing models to analyze the results. Key findings included: 1) Contractors and consultants similarly rated "clear drawings and specifications" as the most important factor; 2) Their rankings of factors were not significantly different, indicating shared views of the cost estimation process; 3) Project costs are more influenced by early design decisions than later construction stages.
1. RESEARCH CYCLE
FACTORS AFFECTING THE ACCURACY OF COST ESTIMATE:
CASE OF JORDAN
Muhammad T. Hatamleh, Mohammed Hiyassat, Ghaleb Jalil Sweis and Rateb Jalil Sweis
Department of Civil Engineering, The University of Jordan, Amman, Jordan
Group Members:
Navodi Gimhani 120457
Tharindu Dodanwala 120339
Roman Man Shrestha 120294
Kaung Wunna Kyaw 120332
Nischaya Sedai 120459
3. FORMULATE
• Problem Statement
• There is no consensus in most important and influential
factors on the accuracy of cost estimate.
• Research Questions
• What is cost estimation?
• What are the factors affecting cost estimation?
• How the factors affect the accuracy of the cost estimation?
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4. FORMULATE (CONTIUNED)
• Objectives
1. To identify and rate the factors affecting the estimation
process
2. To test the degree of consensus among the contractors
and the consultants regarding the ranking of the factors
affecting the accuracy of cost estimation
3. To discuss the top ten factors within the Jordanian
construction companies, justify their high rank and
compare them with other studies
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5. FORMULATE (CONTIUNED)
• Literature Review
• Estimation - Process of predicting and forecasting the
time, cost and other resources needed to accomplish the
objective (Larson and Gray, 2011)
• Cost estimating - Predictive process of quantifying the
financial resources dependent upon the scope of
investment to establish the project budget (Dysert, 2003)
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6. FORMULATE (CONTIUNED)
• Literature Review
• Azman et al. (2013) identified that availability of sufficient
design information and cost data as most important factors
in preparing accurate estimates
• Alumbugu et al. (2014) concluded that the most
influencing factor affecting the accuracy of pre-tender cost
estimation is the experience and skill level of the estimator
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8. GENERATION OF HYPOTHESIS (CONTIUNED)
H0: There is no significant difference between contractors and
consultants toward the ranking of factors related to contractors,
consultants, design parameters, and information.
H1: There is a significant difference between contractors and
consultants toward the ranking of factors related to contractors,
consultants, design parameters, and information.
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9. DATA COLLECTION
Respondents’ information Frequency Percentage
Type of participation in the project implementation
Contractor 170 64.2
Consultant 95 35.8
Working experience in the construction industry
< 3 years 35 13.2
3-5 years 90 34.0
5-10 years 80 30.2
10-15 years 37 14.0
>15 years 23 8.7
Table 1: Demographic Description
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10. DATA EXPLORATION
• To evaluate reliability and validity a pilot study
(30 respondent) was carried out
• Cornbach’s α coefficient test is used for appraisal
of the reliability (0.783 ≤ α ≤ 0.967)
• Spearman test was used to ensure the criterion
and construct validity of the questionnaire (p-
value < 0.05)
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11. MODEL AND MONITOR
• 𝑅𝐼𝐼 =
Σ𝑤
𝐴𝑁
𝑥100% =
5𝑛5+4𝑛4+3𝑛3+2𝑛2+1𝑛1
5𝑛5
𝑥100%
RII- Relative Important Index
w- Weight given to each factor by respondent
(1- not important to 5- very important)
A- Highest weight (5)
N- Total number of samples
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12. MODEL AND MONITOR (CONTIUNED)
Factor
Contractor Consultant
RII (%) Rank RII (%) Rank
Experience of pricing construction projects 81.4 2 82.4 2
Clear and detail drawings and specification 82.4 1 84 1
Availability of database of bids on similar
project
71.4 9 81.6 4
Accuracy and reliability of cost information 75.4 5 77 5
Projects team experience of the construction
type
76 4 74 8
Completeness of cost information 72.2 8 74.6 7
The estimating method used 69.6 11 71.2 9
Level of involvement of the project manager 69.4 12 71.2 9
Quality of information and flow requirements 69.4 12 69.8 12
The quality of the assumptions used in
preparing the estimate
73 7 76.8 6
Time allowed for preparing cost estimates 75 6 74.4 8
Perception of estimation importance 80 3 82.2 3
The padding estimates 68.2 13 70.9 10
Contractor bidding strategy 69.4 12 63.2 13
Table 2: Factors Related to Contractors, Consultants, Design Parameters & Information
Mann-Whitney = 103.5
p-value = 0.708 (p-value >
0.05);
The null hypothesis is therefore
accepted at 95% confidence
interval.
No significant difference
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13. MODEL AND MONITOR (CONTIUNED)
• Conclusions
• There are slight differences between the contractors’ and consultants’
response over the importance factors affecting the accuracy of cost
estimation. This result indicates that each of them looks at the process of
cost estimation almost the same way.
• The ranking of “clear drawing and specification” as the most important
factor indicates that construction project costs were more influenced by
architects and consultants than by contractors. This means that the
project costs are more determined by decisions at the initial, feasibility,
and early design stages rather than by later construction stages.
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